#define _CRT_SECURE_NO_WARNINGS 
#include <stdio.h>
int Fib(int n) {
    if (n == 0 || n == 1)
        return 1;
    else return Fib(n - 1) + Fib(n - 2);
}
int main() {
    int n;
    scanf("%d", &n);
    printf("%d", Fib(n));
    return 0;
}